REGRESSION TESTING -Regression testing is repeated testing of an already tested program in each release or each build after modifications to discover any defects introduced or uncovered as a result of the changes in the product.
RETESTING – Retesting is the testing of a particular module due to the bug fixes,it is basically the act of repeating a test to verify that a found defect (an existing defect which is now fixed) has been correctly functioning.
NOTE – So we can say here retesting is a small part of regression testing in each release.
Thanks for the post on this mostly used topic. In my opinion:
Regression Testing is the execution of all or a select set of test cases which have passed on the previous build or release of the application under test in order to validate that the original features and functions are still working as they were previously. These tests normally will not have already been executed against the current build or release as normally only the new features and functions are tested prior to regression testing.
Retesting is the execution of one or a set of test cases which previously failed due to a suspected defect in the software which now is documented as being remedied.